The field of the present invention is flow control devices and particularly such devices as are employed with intravenous catheters.
With the advent of sophisticated monitoring equipment, it has become common practice in hospitals and particularly in intensive care facilities to maintain a continuous monitoring of certain body functions. This monitoring often includes intravenous sensing requiring a hollow catheter.
The advantages of continuous monitoring of blood pressure and the like using such a hollow catheter have made this practice routine. However, such catheters are subject to blinding by blood clotting over the end in the vein or artery. A relatively successful solution to such blinding has been devised which includes a small medical fluid flow through the catheter. To this end, capillary tubes have been employed. The capillary flow is, however, only a partial solution to the problem. Use of such a system requires a compromise between excessive volumes of flow into the body and insufficient flow to assure against blinding.
To prevent excessive flow into the body and yet provide some means for overcoming clotting, an additional solution has been employed. A manually controlled high volume flow sufficient to insure against blinding of the catheter is used. The high volume flow is also useful for initially filling the catheter line with fluid, for removing air bubbles and the like. Disclosures of such devices incorporating this bi-flow concept include U.S. Pat. No. 3,675,891 entitled "Continuous Catheter Flushing Apparatus" to Reynolds et al. and U.S. Pat. No. 4,192,303 entitled "Flow Restricting Device For Artificial Catheter Systems" to Young et al. The Reynolds et al. and Young et al. patents are incorporated herein by reference as indicative of the prior state of the art and to provide further illustration of utility of the present invention.
A difficulty remaining with the state of the art devices presently employed in hospitals and the like is that they are susceptible to being very inconvenient to use one-handed. Often the operator must be holding another container or in some other way using one hand for other purposes. Consequently, one-handed operation is quite important. Another difficulty is the susceptibility of the rather delicate components of such units to breakage. Heretofore, the valves have been either tricky to manipulate or so fragile as to require careful attention to prevent damage or inoperability.